The present invention relates to a novel quinone diazide compound spectrally sensitized in the visible region and a light-sensitive composition containing the novel compound The present invention also relates to a light-sensitive composition comprising the novel compound, and a photo-sensitive lithographic printing plate comprising the novel compound as a constituent of the light-sensitive layer.
It is a commonly-known fact that quinone diazide compounds have come to be widely used, in combination with alkali-soluble resins, in the field of photosensitive plates and resists. For example, reference is made to J. Kosar, Light Sensitive Systems (John Wiley & Sons 1965), and A. Reiser, Photoreactive Polymers (John Wiley & Sons 1989).
In recent years, image formation methods have been studied which utilize light sources other than state of the art ultraviolet light, such as visible light or near-infra red lasers. Presently, in the making of printing plates, the UV projector light beam method, directly laser-made plates, laser facsimile, holography, etc., have all already reached the practical stage. High sensitivity photosensitive materials which react with these light sources are just being developed. In developing light-sensitive materials for the above-used light sources, the existence of chemical compounds that react with high efficiency to light from the near ultraviolet to the visible and further to the near infra-red region is essential.
The light sensitization in the visible region of various, copolymer-utilizing light-sensitive compositions has been studied. A few of these high-sensitivity light-sensitive compositions are approaching the practical stage as visible light projection plates or visible light laser sensitive materials.
Nevertheless, in spite of the fact that light-sensitive compositions using quinone diazide compounds have been long studied, until now, reports of quinone diazides having spectral sensitization in the visible region are extremely rare, and no spectrally sensitized compounds have yet been proposed which have a degree of sensitivity so that they could be practically used.